The present application relates to stray voltage, and particularly to stray voltage as it affects livestock and the production of such livestock, such as the production of milk by cows on a dairy farm. Stray voltage is a small voltage, generally considered less than 10 V, which may exist between two locations or objects. Stray current is the current produced by stray voltage, generally less than 1 Amp if carried on a 10Ω circuit. When an animal connects the two locations or objects, electricity may flow through the body of the animal. Livestock may avoid certain stray voltage/stray current exposure locations, which may result in a) reduced water intake that may result if annoying or painful exposure is required for animals to access watering devices; b) reduced feed intake that may result if annoying or painful exposure is required for animals to accesses feeding devices or locations, c) difficulty of moving or handling animals in areas of annoying or painful voltage/current exposure; or d) the release of stress hormones produced by contact with painful stimuli.
The existence and detrimental effect of such stray voltage and stray current is the subject of numerous published studies. As a result of such studies, the desire to minimize stray voltage and stray current has become accepted, and the U.S. federal government and several states (including Minnesota) have set out guidelines or standards for defining and acceptable stray voltage levels in agricultural or livestock settings. See for instance the Unites States Department of Agriculture Handbook 696 titled “Effects of Electrical Voltage/Current on Farm Animals: How to Detect and Remedy Problems (commonly referred to as the Red Book) and the “Minnesota Stray Voltage Guide—A Guide Addressing Stray Voltage Concerns”, setting forth that stray voltage levels in excess of a threshold of 0.5 Volts should be avoided and/or addressed. It is quite possible that the 0.5 Volt stray voltage threshold for taking corrective action may change in the future as further study is conducted. See also National Electrical Code section 250.6.
The existence and detrimental effect of stray voltage or stray current is also the subject of several patent documents. U.S. Pat. No. 5,321,318 to Montreuil discloses a system for sensing stray current, which injects a compensatory current in various locations in the ground return circuit associated with one or more saturable reactors. U.S. Pat. Nos. 7,394,259 and 7,405,670 to Fitzgerald disclose a stray voltage detection and isolation system disposed on a water delivery system, and U.S. Pat. Nos. 8,760,837 and 9,021,986 to Straubhaar disclose a system for monitoring and mitigating stray voltage which measures electrical currents flowing through a water pipe.
In general, however, existing guidelines, standards and patent solutions fail to acknowledge and adequately consider the transient and locational nature of stray voltage/current. Stray voltage/current can change significantly over time as electrical conditions and weather conditions on the farm or dairy barn change over time. The best solution to ameliorate stray voltage/current often depends upon the transient nature of the stray voltage or current being witnessed. Further, the direction and/or location where stray voltage/stray current exists can change from time to time, particularly depending upon the root cause of the stray voltage/stray current. Many stray voltages are caused by utility companies, as they providing insufficient wiring for their electrical grid and use the earth to complete circuits. Other stray voltages are caused by mother nature, such as the result of weather patterns, lightening strikes, etc., some of which are recurring or regular in when they occur. Other stray voltages/stray currents are caused by improper wiring of the electrical system including an improper neutral-to-ground connection, by improperly using the grounding path to carry neutral current, and by short circuits or other electrical insulation problems in the electrical equipment on the farm. Some stray voltage causes create stray voltages which are largely direct current, while other stray voltage causes create stray voltages which are primarily alternating current. One type of stray voltage/stray current might affect the farm or dairy barn in one location or one direction, while stray voltage/stray current resulting from a different cause might affect the farm or dairy barn in a different location or different direction. Better methods and systems are needed to identify stray voltage issues and particularly transient, directional and locational stray voltage/stray current issues. More information about transient, directional and locational stray voltages/currents and their effect on livestock may also lead to better, more accurate and more timely correction of electrical sources creating the identified stray voltage/current problems.